Acknowledgments
The authors would like to thank Jing Zhang, Qian Wang, Hai Peng Xu, Wen Na Zhang, Juan Wang, Ding Yang, Jie Li, Fu Yun Qiao, Di Gang Zhi, Hao Hao Qi, Gan Lin Feng and Yuan Yuan Duan from Lanzhou University for the contributions made to this study through their field assistance and laboratory analysis. This study was funded by the Key Laboratory of Superior Forage Germplasm in the Qinghai-Tibetan Plateau (2020-ZJ-Y03), the Changjiang Scholars and Innovative Research Team in University (IRT17R50), the Major Project of Xizang autonomous region (XZ201901NA03) and the National Natural Science Foundation of China (31172258), and the 111 Project (B12002).